1. Field
Aspects of the present disclosure relate generally to wireless communication systems, and more particularly, to an apparatus and method for improving call performance of a Dual-Cell High-Speed Uplink Packet Access (DC-HSUPA) system, thereby providing consistent service in a wireless communication system.
2. Background
Wireless communication networks are widely deployed to provide various communication services such as telephony, video, data, messaging, broadcasts, and so on. Such networks, which are usually multiple access networks, support communications for multiple users by sharing the available network resources. One example of such a network is the UMTS Terrestrial Radio Access Network (UTRAN). The UTRAN is the radio access network (RAN) defined as a part of the Universal Mobile Telecommunications System (UMTS), a third generation (3G) mobile phone technology supported by the 3rd Generation Partnership Project (3GPP). The UMTS, which is the successor to Global System for Mobile Communications (GSM) technologies, currently supports various air interface standards, such as Wideband-Code Division Multiple Access (W-CDMA), Time Division-Code Division Multiple Access (TD-CDMA), and Time Division-Synchronous Code Division Multiple Access (TD-SCDMA). The UMTS also supports enhanced 3G data communications protocols, such as High Speed Packet Access (HSPA), which provides higher data transfer speeds and capacity to associated UMTS networks.
Generally, if the UE follows the current 3GPP Rel-9 standard guidelines, control Protocol Data Units (PDUs) and retransmission PDUs are mostly transmitted on a second carrier rather than a primary carrier. However, if the secondary carrier performance is inferior to primary carrier due to radio conditions, radio link control (RLC) information and/or retransmission PDUs will not reach a network, causing throughput degradation, window stall, RESET etc. which impacts the user and/or call performance. Moreover, if the secondary carrier has a worse radio condition than that of the primary carrier, all of the PDUs (i.e. control PDU, the retransmission PDUs, and new data PDU) are not likely to be transmitted.
Thus, aspects of this an apparatus and method for improving call performance of a DC-HSUPA system via enhancing the RLC PDU retransmission mechanism, lessening throughput degradation, and reducing call drops, thereby providing consistent service in a wireless communication system.